We are studying the (1) validity and precision of ambulatory blood pressure monitoring estimates of blood pressure, (2) feasibility of ABPM in hospital and community-based trials, (3) the independent contribution, if any, of ABPM to characterization of cardiovascular risk prediction, (4) repeatability of ABPM profiles, (5), the impact of specific activities on blood pressure and (6) impact of sodium restriction and weight loss on ambulatory blood pressure.